Keratosis pilaris

An 18 year old presents to your office complaining of a sandpaper-like rash that affects his upper outer arms. He is otherwise healthy and has no other symptoms. The most likely diagnosis is?

• A) scarlet fever
• B) infectious mononucleosis
• C) keratosis pilaris
• D) seborrheic dermatitis
• E) psoriasis

 The answer is: (C). (Keratosis pilaris) 
Keratosis pilaris is defined as hyperkeratotic follicular papules on the extensor surface of the upper arms or upper anterior thighs and occasionally on the malar area of the face. It may be associated with atopy and dry skin.
A sandpaper-like feel is noted in these isolated areas. The condition is considered benign and is treated with topical lactic acid cream or lotion. Lesions that are associated with the face typically resolve at puberty.